docs: def usage(self, subcommand):
          """
          Return a brief description of how to use this command, by
          default from the attribute ``self.help``.
      
          """
          if len(self.option_list) > 0:
              usage = '%%prog %s [options] %s' % (subcommand, self.args)
          else:
              usage = '%%prog %s %s' % (subcommand, self.args)
          if self.help:
              return '%s\n\n%s' % (usage, self.help)
          else:
              return usage